ARM: dts: sun5i: Add port E pinmux settings for mmc2

ARM: dts: sun5i: Add port E pinmux settings for mmc2

These alternate pins for mmc2 are brought out to the 40 pin U14 header
on the C.H.I.P and can be used to add an external MMC device with a 4
bit interface. See

https://byteporter.com/ntc-chip-micro-sd-slot/

for further details on how.

Signed-off-by: Jonathan McDowell <noodles@earth.li>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/7949169f581cab37175602188f44bc26e79a45c0.1683719613.git.noodles@earth.li
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>